1. Field of the Invention
The present invention relates in general to a printing apparatus wherein printing is effected on a recording medium while the medium is fed in a direction of printing, and more particularly to a feeding device having a driving feed roller for feeding the recording medium such that the feed roller is in rolling contact with a surface of the medium.
2. Discussion of the Prior Art
In a printing apparatus of the type indicated above, the recording medium is fed in the printing direction in which the recording medium is moved relative to a print head. In a known printing apparatus of this type, a pair of feed rollers are usually provided to feed the recording medium in the printing direction such that the feed rollers are adapted to be held in rolling contact with the opposite surfaces of the recording medium and are rotated about respective axes perpendicular to the printing direction.
Usually, the recording medium used for this printing apparatus takes the form of a web or tape, which is fed in its longitudinal direction so that desired lettering characters or graphic designs are printed in a predetermined printing area which extends in the longitudinal direction of the medium. The printed portion of the tape or web which bears desired images is cut off and is used as a dry image transfer sheet or decalcomania sheet, for which the images are transferred to a desired image-receptive member.
While dry transfer sheets for lettering purposes are commercially available, the users are often forced to buy the dry transfer sheets which include letterings or graphic designs other than those which are desired or needed by the users. If the image to be transferred consists of a word, for example, the users are required to transfer the individual letters of the word from a dry transfer sheet or sheets, one after another, while registering the transferred letters.
In view of the disadvantages of the commercially available dry transfer sheets, there has been proposed a printing apparatus of the type described above, by which the users can prepare dry transfer sheets which bear desired original images such as words, phrases or graphic designs to be transferred to a desired image-receptive member. For instance, Japanese Patent Application No. 61-305539 discloses a thermal tape printer. In this thermal printer, a thermal print ribbon is superposed on a recording tape which has a specially processed recording surface. Printing is effected on the recording surface of the tape, such that an ink composition is transferred from the thermal print ribbon to the recording surface of the tape, by selective energization of heat-generating elements of the print head. Thus, a desired lettering tape or dry transfer tape which bears an image formed by the transferred ink composition is prepared by thermal mass transfer printing. The prepared dry transfer tape is placed on the desired image-receptive member, and a finger-pressure is applied to the back of the tape to transfer the image from the dry transfer tape to the surface of the image-receptive member.
As indicated above, the recording tape is fed in the printing direction by a pair of feed rollers, which are disposed downstream of the print head in the printing direction. On the other hand, the recording surface of the tape has a relatively low degree of wettability, for easy transfer of the printed image from the recording tape to the image-receptive member. Accordingly, the printed image tends to be easily transferred to the outer circumferential surface of one of the two feed rollers which is held in rolling contact with the recording surface of the tape while the tape is fed. This indicates partial or complete removal or erasure of the printed image from the prepared dry transfer tape, and re-transferring of the ink composition from the feed roller to the printing area on the recording surface of the printed tape.
A similar drawback is experienced where the tape printer is used for printing desired images on a recording medium which is not used as a dry transfer sheet. For example, the printed recording medium is directly applied by an adhesive to a desired article. While the recording surface of the medium used in this case has a relatively high degree of wettability, the printed images on the medium is more or less adversely influenced by the contact of the feed roller with the recording surface of the medium.